i8o 



GYMNOSPERMS 



so highly developed that the megaspore mcmlirane must have be- 

 come too thin to give much protection. 



Tlic embryo. — As in the Cycadofilicales, no embryo has yet been 

 found. Immense numbers of American coal balls, with well-pre- 



FiG. 192. — Cordaianthus penjonii: longitu- 

 dinal section of male strobilus showing bracts 

 and sporophylls bearing terminal microsporan- 

 gia; Xio. — After Renault.^'s 



Fig. 193. — Cordaianthus 

 penjonii: the sporophyll in 

 the middle bears four 

 microsporangia. The one 

 at the right has shed its 

 pollen; X23. — After Re- 



NAULT.-»*5 



served structures, have been collected and still remain to be sec- 

 tioned. They may contain the missing stages in the life-history. 



PHYLOGENY 



The Coniferophytes have been contrasted with the Cycadopnytes 



as having branched sli-nis and unl)ra'uhe<l leaves, while the Cycad- 



